I did mean Ryanair, not Dandair, showing my age!
For the record Linz-Vienna-Bratislava is an excellent bike path trip and great week away, if an eeny but dull just west and east of Vienna. Otherwise good countryside, paths you could ride on 23s, plenty of info places, maps, signs and places to stay. If we did it again we would take two days longer and go from Passau west of Linz. Ryanair took the tandem both ways for bike payment (it's a bulky sporting item) and there were no problems or damage. I'd bagged it and lashed front wheel and both sets of bars to side of frame. Bit of split plastic tubing over lower connecting chain and over bar end shifters, and between fork ends. Weighed 24.5 kilos, but it does have Marathon XRs! Panniers went in an onion bag, weighed 13kilos and counted as one item. Recommend it to anyone as first tandem trip by plane - as it was ours. Thorn Voyager faultless and normally very stable -- though quite wobbly if you try to ride it with panniers on and stoker off.